1. Technical Field
This present disclosure relates generally to video/audio content transport and more particularly to the transmission of such video/audio content in a wireless system.
2. Related Art
The broadcast of digitized video/audio information (multimedia content) is well known. Limited access communication networks such as cable television systems, satellite television systems, and direct broadcast television systems support delivery of digitized multimedia content via controlled transport medium. In the case of a cable modem system, a dedicated network that includes cable modem plant is carefully controlled by the cable system provider to ensure that the multimedia content is robustly delivered to subscribers' receivers. Likewise, with satellite television systems, dedicated wireless spectrum robustly carries the multi-media content to subscribers' receivers. Further, in direct broadcast television systems such as High Definition (HD) broadcast systems, dedicated wireless spectrum robustly delivers the multi-media content from a transmitting tower to receiving devices. Robust delivery, resulting in timely receipt of the multimedia content by a receiving device is critical for the quality of delivered video and audio.
Some of these limited access communication networks now support on-demand programming in which multimedia content is directed to one, or a relatively few number of receiving devices. The number of on-demand programs that can be serviced by each of these types of systems depends upon, among other things, the availability of data throughput between a multimedia source device and the one or more receiving devices. Generally, this on-demand programming is initiated by one or more subscribers and serviced only upon initiation.
Publicly accessible communication networks, e.g., Local Area Networks (LANs), Wireless Local Area Networks (WLANs), Wide Area Networks (WANs), Wireless Wide Area Networks (WWANs), and cellular telephone networks, have evolved to the point where they now are capable of providing data rates sufficient to service streamed multimedia content. The format of the streamed multimedia content is similar/same as that that is serviced by the limited access networks, e.g., cable networks, satellite networks. However, each of these communication networks is shared by many users that compete for available data throughput. Resultantly, streamed multimedia content is typically not given preferential treatment by these networks.
Generally, streamed multimedia content is formed/created by a first electronic device, e.g., web server, personal computer, user equipment, etc., transmitted across one or more communication networks, and received and processed by a second electronic device, e.g., personal computer, laptop computer, cellular telephone, WLAN device, or WWAN device. In creating the multimedia content, the first electronic device obtains/retrieves multimedia content from a video camera or from a storage device, for example, and encodes the multimedia content to create encoded audio and video frames according to a standard format, e.g., Quicktime, (motion picture expert group) MPEG-2, MPEG-4, or H.264, for example. The encoded audio and video frames are placed into data packets that are sequentially transmitted from the first electronic device onto a servicing communication network, the data packets addressed to one or more second electronic device(s). The sequentially transmitted sequence of encoded audio/video frames may be referred to as an audio/video stream. One or more communication networks carry the data packets to the second electronic device. The second electronic device receives the data packets, reorders the data packets if required, and extracts the encoded audio and video frames from the data packets. A decoder of the second electronic device decodes the encoded audio and/or video frames to produce audio and video data. The second electronic device then stores the video/audio data and/or presents the video/audio data to a user via a user interface.
The audio/video stream typically traverses a number of differing types of communication networks, e.g., LANs, WANs, the Internet, WWANs, WLANs, one or more cellular networks, etc. Some of these networks may not support the audio/video stream reliability and/or with sufficient data rate, resulting in poor quality audio/video at the second electronic device. In particular, wireless networks have limited throughput shared by multiple users and can suffer from environmental conditions that interfere with wireless transmissions. Nonetheless, these wireless networks are called upon to support high bandwidth usage video streaming.